The present invention pertains generally to instruments used in intraocular ophthalmic surgery within the lens capsule (referred to herein as intracapsular ophthalmic surgery, not to be confused with the specific procedure sometimes called intracapsular cataract extraction of ICCE), and in one aspect of the invention to instruments for retaining the lens capsule in a stable, centered position during surgery.
In modern cataract surgery, a short incision is made along the margin of the cornea for access to the lens through the central opening of the iris (pupil). A circular opening is cut or torn in the anterior capsule (capsularhexis), and in the case of a cataract, the clouded lens is removed, such as by phacoemulsification. Preferably, the posterior portion of the lens capsule is left intact so that the posterior chamber remains isolated from the vitreous. Also, the zonules are not disturbed so that the opened lens capsule continues to be supported and centered in the posterior chamber. Thereafter, an artificial lens is implanted in a manner well known in the art.
Aging results in changes in characteristics of various parts of the eye, such as the zonules. The centering force of the zonules is not strong. Over time, the zonules can become weaker or may be partly missing, thus less reliable in centering the capsule beneath the iris because different forces may be applied at opposite sides of the capsule. This can create a problem for the surgeon because performing the lens replacement may be more difficult if the lens capsule is not centered, and the surgery itself may introduce unnatural stresses that could damage weak or brittle zonules.